In order to facilitate the ultimate production of a diagnostic and vaccine for human viral NANB hepatitis using recombinant DNA technology, strategies designed to isolate viral nucleic acid will be initiated through the production of enriched recombinant cDNA libraries and by direct radio-labeling studies. In addition, monoclonal antibodies will be made against virus preparations and an in vitro system for propagating virus investigated. An association of reverse transcriptase activity with virus will also be investigated. Progress in these areas should lead to the molecular cloning, characterization and recombinant expression of the virus genome which in turn will allow diagnostic development and subsequent vaccine approaches.